code: def test_concat(styler):
      result = styler.concat(styler.data.agg(["sum"]).style).to_string()
      expected = dedent(
          """\
       A B C
      0 0 -0.61 ab
      1 1 -1.22 cd
      sum 1 -1.830000 abcd
      """
      )
      assert result == expected
  
file_path: pandas/pandas/tests/io/formats/style/test_to_string.py
imports: from textwrap import dedent
  import pytest
  from pandas import DataFrame, Series
  from pandas.io.formats.style import Styler
label_desc: Use image node_id 5 for calling a global function with example usage: test_concat(styler) without return types